The present invention is directed to a method for dehydrohalogenating halogenated compounds, and more particularly, to a safe and effective method for disposing of dangerous halogenated compounds like ethylene dibromide by dehydrohalogenation.
Ethylene Dibromide, also known as dibromo ethane (EDB), was at one time commonly used as a pesticide and spot fumigant. It has recently been determined that the use of EDB as a pesticide and spot fumigant is a major health risk to the general public and especially to people, like mill workers, who handle the products sprayed with EDB. The pesticide is now known to be carcinogenic to humans. Since EDB was also used as a fumigant at grain mills and at grain storage facilities, there is also a significant cancer risk to the general public via intake of those grains.
The toxic properties of EDB mandated the cancellation of its registration by the Environmental Protection Agency (EPA). This cancellation resulted in the need to dispose of thousands of gallons of EDB. Incineration is not considered a safe method. Accordingly, there is now a need for a safe and effective method to dispose of the cancelled EDB and similar compounds.
Known methods for destroying various halogenated compounds similar to EDB involve the use of polyethylene glycols. With several such methods, there does not appear to be any dehydrogenation. U.S. Pat. No. 4,327,027 to Howard et al describes the dehalogenation of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) by reaction with an admixture of an alkali metal hydroxide and an alcohol. This process is completed at very high temperatures, generally at 160.degree.-180.degree. C. Pytlewski et al, U.S. Pat. No. 4,337,368 discloses the decomposition of polychlorinated biphenyl (PCB) by reaction with sodium polyethylene glycol and oxygen. The decomposition products are identified as polyhydroxylated aromatics.
A further method, in U.S. Pat. No. 4,353,793 to Brunelle, involves the dechlorination of PCB by reaction with low molecular weight polyethylene glycol ethers and potassium hydroxide. The reagant is described as a monocapped-polyalkyleneglycol alkyl ether.
U.S. Pat. No. 4,447,541 to Peterson dehalogenates various polyhalogenated compounds present in the soil as contaminants with a reagant comprising potassium hydroxide and polyethylene glycol. This reaction, however, requires a sulfoxide catalyst.
More relevant here is the Strosacker reference, U.S. Pat. No. 2,322,258, which discloses the dehydrohalogenation of polyhalo aliphatic hydrocarbons such as ethylene dibromide (EDB) to produce the corresponding halogenated olefin, in the case of EDB, vinyl bromide. The reagant is an admixture of a polyhydric alcohol, which is prefererably tetraethylene glycol, and an alkaline reactant, which may be potassium hydroxide. This process, however, uses approximately 0.0001 mole of the glycol catalyst per mole of the alkali metal and, consequently, the reactants must be heated to 50.degree.-150.degree. C. or in order for the catalyst to form a solution which will dissolve the alkali. A salt crust would otherwise form around the alkali and impede the reaction.
None of the known methods have met the criteria required to provide a safe and efficient process to destroy the halogenated compounds that comprise contaminants. Destruction of the compound without release of toxic pollutants into the environment is clearly important. Thus, a process which produces by-products that are not toxic is most important. It would be advantageous if the method could be conducted on-site and would not require specialized containers and equipment for handling the by-products. It is also desirable to have a process which does not require high temperatures.
Therefore, it is an object of the present invention to provide a method for the total dehydrohalogenation of halogenated compounds.
It is a further object of the present invention to provide a safe and efficient method to dispose of toxic soil and environmental contaminants containing one or more halogenated compounds by total dehydrohalogenation of the halogenated compound or compounds.
It is another object of the present invention to provide an on-site method to dispose of toxic environmental contaminants, like ethylene dibromide, which does not require high temperatures.
It is still another object of the present invention to provide a method for the total dehydrohalogenation of halogenated compounds which produces by-products that are non-toxic and do not require specialized containers and equipment for handling.
Still another object of the present invention is to provide a method for the dehydrohalogenation of halogenated compounds forming recoverable by-products which may be recycled or even sold.